JPS6119297B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for metering and/or dispensing fluid materials, in particular dry granular materials and semi-liquid materials, into a pressurized or unpressurized atmosphere.

Finely divided particulate materials such as Gunite, a mixture of sand and cement, are difficult to supply. feeding the dry sand-cement mixture with compressed gas to a nozzle where the mixture is wetted with an appropriate amount of water and applied to the working surface;
Various methods are known. Generally, prior art machines utilize pressure vessels, pressurized multiple chambers, or tapered rotary valves.

Allentown Pneumatic Gun Company
manufactures feeding devices with single or dual chambers. In the case of two chambers, the material is evacuated from the lower chamber by compressed gas while the upper chamber is being filled with material. Workers are required to cycle the supply of material from the upper chamber to the lower chamber. The upper chamber must be vented to atmosphere before refilling.

The Nucrete pneumatic atomization device, manufactured by the Nucrete group of companies in Melbourne, Australia, consists of a paddle mixer that discharges the granular material being fed into a feed chamber. Within the feed chamber, a chain drive with a fixed disc pulls a continuous stream of material through the rubber tube. Part way down the length of the tube, a series of air jets blows the material between the fixed discs and through the hose. Although pressure vessels are not required, wear and maintenance are issues.

Another type of equipment, manufactured by the Schulenbergbetton-Schuplicz Maschinen (SBS) company in Etzel, West Germany, is a rotary taper with multiple chambers for intermittently feeding material into a pressurized chamber. It uses a valve. The problem is wear and sealing of this tapered valve. Also, the chamber within the rotary valve must be vented to atmosphere after evacuation of material and before refilling.

NSF Industries, Troy, Michigan, manufactures units that employ multi-chamber rotors mounted within housings. Compressed air enters through a fixed rotor liner containing openings in communication with the rotor chambers and forces material out of the respective chambers. Intraday AG of Switzerland manufactures a unit that operates on a similar principle.

Some of the machines in use today require venting, which limits production capacity. Venting also creates dust-sweeping problems, resulting in waste of pressurized gas.

Peristaltic pumps for pumping fluid and semi-fluid materials are known. U.S. Pat. No. 2,015,123 discloses the method of receiving blood from a blood donor by compressing the blood-filled tube using a worm that is placed parallel to and rotated to impart a peristaltic motion to the tube. A device for transferring blood to a container is disclosed. U.S. Pat. No. 2,629,333 discloses a fluid having a resilient wall tube and a rotatable helical member such that the helical member engages and progressively compresses the tube as the helical member is rotated. Discloses a pump. US Pat. No. 3,669,574 discloses a peristaltic pump for submersible pumping of fluids.

U.S. Pat. No. 3,754,683 discloses an apparatus for supplying dry particle acceleration material for concrete into a suction air stream working in combination with a peristaltic pump.

The present invention discloses a metering and dispensing unit for fluid materials that employs at least one vertically oriented resilient wall tube to retain the material to be dispensed. A power-driven assembly having tube means is positioned along the length of the tube and adjacent thereto, the tube means moving the tube starting at the supply end of the tube and moving progressively toward the discharge end thereof. for engaging a portion of the tube in a compressive manner against itself;
At the discharge side, the tube is allowed to re-expand and the material within the tube is expelled from the discharge end of the tube. Valve means are provided to permit fluid material to enter the supply end of the tube at periodic time intervals, with one of the tube means of the power-driven assembly first engaging the tube and causing the valve to enter the supply end of the tube. Valve means operate in coordination with the powered assembly such that when the tube is crushed, the portion of the tube being crushed is substantially free of material. The material may be discharged from the discharge end of the tube into a plenum through which a pressurized flow of gas is directed to carry the material to the work site. Multiple units or other means may be used to provide a continuous flow of material, as described below. We describe two types of units that function similarly in many respects.

FIG. 1 shows a metering and/or dispensing unit for fluid materials. The unit consists of a lower plate 12 and a side plate 1 separated by an upper plate 11 and an intermediate support plate 13.
4 and a housing 10 for a dosing unit. As shown in FIG. 2, mutually opposing openings are provided in the upper and lower plates, these openings being positioned adjacent to the support plate 13. Support plate 13 can be made adjustable with respect to its distance from the respective openings in plates 11 and 12, if desired. The opening in the upper plate 11 includes a flange 15 around it. The flange 15 is attached to the upper plate 11
extends above and below the surface of the

An open-ended resilient wall tube 17 is secured around the lower portion of flange 15 at its upper or supply end and at its lower or discharge end. The tube 17 is secured at its upper end by a strap or clamp 18. A similar clamp 16 can be used to secure the lower or discharge end of the tube around the flange of the sleeve that extends into the opening in the lower plate 12. Resilient tube 17 is preferably made from a woven and reinforced rubber material having an inner wall with a smooth surface. Its thickness ranges from about 0.635 cm to 1.905 cm, with 1.27 cm being preferred. A resilient pad 19 (approximately 1.27 cm thick) is provided between the tube 17 and the support plate 13 and extends the length of the tube, providing a resilient backstop between the tube and the support wall 13. give.

A drive assembly is mounted within the frame including a tube roller mounted to engage a portion of the tube, the tube roller beginning to compress the tube engaging portion at its feed end against the tube itself; It is then actuated progressively downwardly toward the discharge end of the tube, at which point the tube roller disengages from the tube to allow tube re-inflation. The tube rollers are mounted on the endless belt at spaced intervals, as shown in FIG. In FIG. 2, a pair of chains 22 are
It extends around spaced apart sprockets 23, 24, and 25. Sprocket 23, 24, 25
are fixed to respective shafts 23a, 26, 27, each shaft being connected to a plate 3 fixed to the side wall 14 of the housing.
1 and 32, respectively, in bearings 20 fixed to the upper ends thereof (see FIG. 3). Sprocket 24
and 25 are mounted to provide a path along substantially the entire length of the elastic tube 17. Three tube rollers 28 are attached to the chain at spaced intervals, with each tube roller 2
8 are rotatably supported in respective bearings on a shaft 29 to rotate around the respective shafts (see FIG. 3). A guide roller 30 is journalled on the end of each shaft 29 and moves along the leading edge of a guide plate 31 fixed to each side wall 14 of the unit. Guide surface 31a (see Figure 2)
Once each tube roller 28 engages tube 17 at its upper or feed end (FIG. 2) and crushes the tube against itself, as the tube rollers advance along the length of the tube ensuring that the tube remains crushed. Plate 32 is pivotally connected to each side wall 14 at 32a. A chain tensioning wedge 32b is provided for adjusting sprocket 23 to tension chain 22.

As shown in FIG. 2, multiple pairs of side roller units 33 can be secured to respective chains 22 between each of the tube rollers. Each side roller unit 33 includes an elongated bracket 34 from which a respective shaft 35 extends. The rollers 36 are rotatably supported on respective shafts 35 . Flanges 37, fixed at one end to the shaft 35, are fixed at their opposite ends to respective pairs of chains. As shown in FIG. 4, the distance between the pairs of rollers 36 should be approximately the same as the diameter of tube 17. The side roller units are designed to contact the walls of the tube after the tube has been crushed by the tube rollers 28 to help reinflate the tube from the shape shown in FIG. 3 to the shape shown in FIG. ing.

In FIG. 2, a relatively short length tube piece 38 is secured around the feed opening in the upper plate 11 using a band or wire clamp 18a. The free end of the resilient tube piece 38 is opened and closed by valve means, such as an arcuate piece of a wheel 39, which is rotationally fixed to the shaft 40 above the supply opening. The shaft 40 has a box 41 which receives and holds the fluid material to be fed into the metering unit.
It is rotatably supported on a bearing fixed to the side wall of the Wheel 39 includes an arcuate surface portion 42 that engages the free end of resilient tube piece 38 to seal the feed opening at regular intervals to prevent material from entering tube 17. .
Rather than the valve means shown, cam actuated slide valves or other valve means functioning to open and close the supply opening at appropriate times may be used.

The drive assembly for tube roller and wheel 39 is driven by suitable means, such as a motor 43 (FIG. 1) having an output shaft that drives sprocket 25. The output shaft has a sprocket 44 fixed to it and a chain 45 wrapped around a sprocket 46 fixed to the shaft 40.
is wrapped around sprocket 44. The relative rotational speed of the wheel 39 to the rotational speed of the drive assembly is such that when the tube roller 28 first engages the tube at its upper end, the feed end of the tube is sealed from material and therefore is chosen to ensure that the tube is substantially free of material, thus allowing the tube to be crushed against itself by the tube roller.

FIG. 5 schematically shows the operation of the unit. In FIG. 5D, arcuate surface 42 of wheel 39 seals the feed end of tube 17 to prevent material from entering tube 17. Tube roller 28a begins compressing tube 17 near the feed end of the tube, crushing the tube against itself. tube roller 28
As a moves progressively down the tube,
Particulate material previously fed into the tube during an earlier cycle moves down the tube.
In FIG. 5A, the upper tube roller 28a
completely collapses tube 17 against itself prior to opening of the feed end of the tube by rotation of wheel 39. In FIG. 5B, lower tube roller 28b reaches the end of its path and disengages from tube 17, allowing material within the tube to be ejected from the tube. At the same time, the material from box 41 is transferred to tube 17 at the top end.
Continue to supply into the. In FIG. 5C, before tube roller 28C contacts the tube near the top or feed end of the tube, arcuate wheel 39
surface 42 closes the feed end of tube 17.
This cycle of operation continues until the material in the box is exhausted.

The material discharged from the tube 17 is shown in FIG.
It may be vented into a pressurized air plenum 47, as shown in FIGS. 2 and 5, or in any other desired manner. It may be desirable for some operations to provide a continuous flow of material, rather than the discontinuous flow of material provided by one such dispensing unit.
Continuous flow can be achieved in a number of ways, three of which are illustrated in FIGS. 6, 7, and 8. FIG. 6 shows three side-by-side dosing units driven through a common drive shaft. The respective positions of the tube rollers 28 and arcuate circular members 39 of each unit are such that the air plenums 4
7 is adjusted to provide a continuous flow of material into the tube. In unit A in FIG. 6, the positions of tube roller 28 and wheel 39 are as follows:
a position such that the feed end of the tube has just finished opening and the lower tube roller has just disengaged from the tube to allow the material in the tube to be fed into the plenum 47 as shown in FIG. 5B. It is. The next adjacent unit (Unit B in Figure 6) has its tube rollers 28 and wheels 39 in a position similar to Figure 5D, where the material has finished being charged into the tube and is moving progressively down the length of the body, but has not yet finished expelling. The next adjacent unit (Unit C in Figure 6) has its tube rollers 28 and wheels 39 in positions similar to those shown in Figure 5C, where the loading of material into the tube is completed. The feed end of the tube is connected to the surface 42 of the wheel 39 to prevent further material from entering.
It is sealed by. By staggering the cycles of each side-by-side unit, a continuous flow of material into the air plenum 47 can be provided.

FIG. 7 shows another method of providing a continuous flow of material into the air plenum. In FIG. 7, the extension 48 of the tube 17 is
extends from the discharge end of the air to the air plenum 47. A butterfly wheel 49 with spaced vanes extending from the central axis of the wheel forms the extension 4 of this tube.
It is rotatably mounted within the range of 8. The material discharged from the tube 17 is prevented from entering the air plenum 47 all at once by the blades of the butterfly wheel. As material is discharged from the discharge end of the tube into the upper extension 48 of the butterfly wheel, the wheel is rotated at a speed sufficient to provide a continuous flow of material into the plenum.

Figure 8 shows another example that provides a continuous supply of material.
We will show you two methods. In this case, the discharge end of the unit is coupled to a pneumatic feeder of the type manufactured by Schulenberg Beton Schuplitzmaschinen (SBS), Essen, West Germany.
The material is discharged into a chamber 50 containing a rotating drum 51. Chamber 50 has a material outlet near its lower end. The pressurized air is discharged through the exhaust conduit 5
2 and discharges it with the material in the chamber.

FIG. 9 shows a vacuum pressure system making use of the dosing unit of the present invention. In Figure 9,
The unit is enclosed within a housing 56 that is coupled to a vacuum source 54. The box above the unit that holds the material to be fed is also connected to the vacuum source 54 and material feed line 57. The vacuum created in box 58 helps draw the material to be fed through line 59 where it is fed by gravity to the upper end of tube 17 of the dosing unit, as previously described. A filter 60 may be provided within the box to prevent material in the upper portion of the box from being drawn into the vacuum pump 54. The vacuum drawn on the dispensing unit outside the tubes 17 assists in re-expanding the tubes to their original condition after they have been crushed by their respective tube rollers 28.

The preferred dosing unit shown is capable of moving relatively large volumes of fluid material economically and with virtually no maintenance. For example, a resilient tube with a diameter of about 7.62 cm can be used to move about 3.823 m ³ of material per hour. Approximately 6.10 m ³ of material can be moved per hour using a 10.16 cm diameter tube.
Using a 30.48 cm diameter tube to feed 3.0 m slugs of material between each tube roller, approximately 400 m ³ of material per hour is fed when 30 slugs per minute are fed into the air plenum. It can be moved. As shown in Figure 6, three units can be used to move approximately 1200 ^m3 of material per hour.

Other units are shown in FIGS. 10-17. This unit utilizes a rotatable helical member which, as it rotates,
It circumferentially engages and compresses one or more vertically oriented tubes, beginning at the supply end and terminating at the discharge end of the tube. a selected time interval to prevent material to be conveyed from entering the tube such that when the helical member engages and compresses the tube, that portion of the tube is substantially free of material; Includes means for periodically covering and exposing the feed end of the tube. The material is discharged from the discharge end of the tube or tubes into a plenum through which a flow of pressurized gas is directed that conveys the material to the work site.

FIG. 10 has an upper plate 71 and a lower plate 72,
Upper and lower plates 71 and 72 are connected by side walls 73. The housing for the dosing unit is shown. The upper and lower plates have a plurality of annular openings 7 equally spaced around the central axis of the housing.
Contains 4 and 75. The housing may also include vertical supports 76 (FIG. 13) at spaced intervals. The side walls are bolted to the upper and lower plates, respectively. Suitable gaskets are provided near the upper and lower edges of the side walls and near the side edges to seal the unit. The gasket near the side edges contacts vertical supports 76.

An axis 77 coincident with and parallel to the axis of the housing extends through respective openings in the top and bottom walls of the housing, as shown in FIG. The shaft is pivoted for rotation relative to the housing through bearings 78 mounted in the top and bottom openings of the shaft. A rigid helical member 79 is attached to and surrounds the shaft, the function of which will be described below.

A plurality of elastic tubes 80a-80b mounted within a modular retainer 81 surround the shaft (see FIG. 13). Each retainer includes a back wall, a top wall 83, and a bottom wall 84. The top and bottom walls wrap around openings 85 and 86, respectively, and
5 and 86 coincide with openings 74 and 75 in the top and bottom walls of the housing, respectively. The elastic wall tube 80 of each retaining unit is clamped at its upper end around a serrated fitting 85a surrounding an opening 85. The tube is cut to provide a smooth inner surface between the inner wall of the serrated fitting 85a and the inner surface of the resilient tube. A four-part clamp 85b is used to tighten the tube around fitting 85a. Similarly, the lower end of the elastic tube piece is clamped around opening 86 by similar means. A smooth interface is provided between the inner surface of the tube and the fitting 86a surrounding the opening 75. Clamp 86b tightens the tube around the fitting. Rear stopper 87 made of rubber or other resilient material (suitable thickness is about 1.27 cm)
is mounted between the rear wall 22 and the tube 20 so as to contact the side wall of the resilient tube adjacent the rear wall of the retainer.

Each module retainer 81 is mounted within a housing as shown in FIGS. 10 and 13. Each of the modular retainers has a bottom wall 72
A shoulder 89 formed on the bottom wall 84 of each module retainer 81 is retained within the housing by a series of pins 88 extending upwardly from the bottom wall 72.
is in contact with. Although not shown, there is a corresponding pin extending downwardly from the top wall 71 against which a shoulder 89 formed on the top wall 83 abuts. Additionally, retaining screws 90 threaded into and extending from the upper and lower walls 70 and 72 are used to retain the bottom wall 84 and top wall 83 of each of the modular units;
This prevents each unit from shifting sideways. This is best shown in FIG.

In FIG. 10, a cover 91 covers at any given time several of the spaced apart openings 74 through which the particulate material falls into each resilient tube. The cover is secured to shaft 77 by spaced supports 92 and 93 for rotation therewith, sequentially covering and exposing each opening 74. A hopper 94, which holds particulate material to be fed into the metering unit, has its discharge end fitted around the top 71 of the housing, as shown in FIG. If desired, a vent opening to the atmosphere can be provided through the support 98 in the cover 91 and the shaft 77 so that the tube can be re-expanded after it has been compressed by the rod.

A plenum 95, into which pressurized air or other gas enters through openings 96, is secured to the bottom wall 72 and overlies each of the bottom openings 75 through which particulate material is discharged. The plenum includes a discharge end that conveys material to the work site.

The housing is sealed and the interior of the housing is filled with oil, lubricant or other coolant.
In the diagram shown in FIG. 15, the housing initially opens valves 98 and 99 and opens valves 100 and 10.
1 and 102. The hermetic filler cap 103 containing the integral dipstick is opened and the housing is filled with oil.
The filler cap is then closed and the vacuum pump 1
04 is started. A vacuum gauge 105 may be included to monitor vacuum. The volume of oil held by the accumulator container 106 should be approximately equal to the volume of oil held within the housing.

When it is desired to drain oil from the housing, filler cap 103 is opened and valves 99, 100 and 102 are opened.
is opened and valves 98 and 101 are closed.
Pump 104 is operated until oil is transferred to container 106. To return the oil to the housing,
Valves 99 and 100 are closed and valves 98, 101 and 1
02 will be held. When operated, the pump 104 creates a vacuum within the housing and pressure within the accumulator. Once all the oil has been transferred, valve 102 is closed.

To prevent lateral movement of each resilient wall tube 80 when it is engaged by the helical rod 79, each of the tubes is fitted with a flexible sling 1.
07 (Fig. 13), and is held within the sling 107
The rivet 1 is placed along the side of the backstop where the rod 79 first engages the elastic tube.
08 (FIG. 14) or other suitable means to the backstop. The sling is approximately
Suitably manufactured from a reinforced elastomeric material such as neoprene having a thickness of 0.318 cm.

The resilient tube 80 preferably has a wall thickness of about 1.27 cm and is fabricated from a woven reinforced rubber material having an interior wall with a smooth surface.

10 and 17, the particulate material held within the hopper 94 is removed from each of the elastic tubes 80e, 80f, 8 which are not covered by the cover 91.
0g, and falls into 80h due to its own weight. In Figure 17, reference numeral 109 refers to the area where the helical rod 79 first engages the resilient tube and compresses it against the opposite side wall of the tube (see Figure 16). In FIG. 17, cover 91 covers tubes 80a, 80b, 80c, and 80.
Note that it covers d. As the helical rod rotates, an air gap 110 is created beneath the cover 91. When the helical rods 79 engage each of the resilient tubes 80 at their upper ends, the material within the tubes prevents the tubes from flattening or compressing against their opposing walls as shown in FIG. It is necessary to have this air gap so that there is no air gap. The material within each of the tubes falls under its own weight from the open discharge end of the tube into the airflow flowing forcefully through the plenum, where it is carried by the airflow for delivery to the desired work location. Compression of the tube by the helical rod disturbs the tube and prevents the material within the tube from solidifying.

The helical rod 79 and shaft 77 can be driven by a hydraulic motor 111, as shown in FIG. Hydraulic fluid is supplied to tank 113 by power source 114.
through line 112 to the hydraulic motor. Hydraulic fluid returns to the reservoir via line 115.

If desired, different materials can be fed into each of the resilient wall tubes and discharged into different respective plenums or discharged into a common plenum for mixing. In addition, the illustrated cover 9
In addition to 1, any means for periodically opening and closing the supply end of each elastic tube may be used. This device can be used for batch materials for mixers or other applications. In this case, the plenum and air conveying means can be omitted.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a preferred unit of the invention. Figure 2 shows the unit 2 in Figure 1.
FIG. 2 is a vertical sectional view taken along the 2nd cutting line. FIG. 3 is a horizontal cross-sectional view of this unit taken along section line 3--3 in FIG. FIG. 4 is a horizontal cross-sectional view of this unit taken along section line 4--4 in FIG. 5 is a series of schematic diagrams showing the unit of FIG. 1 in operation; FIG. 6 is a perspective view of three units of the type shown in FIG. 1 mounted in side-by-side relationship for continuous supply of material; FIG. FIG. 7 is a partial cross-sectional view showing another means for providing a continuous flow of material from a unit such as that shown in FIG. 1 into an air pressurized plenum. FIG. 8 is a partial view showing another method of continuously providing material from a unit of the type shown in FIG. FIG. 9 is a schematic diagram of a vacuum pressure system employing a unit of the type shown in FIG. FIG. 10 is a perspective view of another type of metering and/or dispensing unit of the present invention.
FIG. 11 is a schematic perspective view of the unit of FIG. 10. FIG. 12 is a horizontal cross-sectional view of the unit of FIG. 10. FIG. 13 is a perspective view of a single modular unit including a resilient wall tube and its attachment. FIG. 14 is a partial horizontal sectional view of a single resilient wall tube and its corresponding holding down means.
FIG. 15 is a schematic diagram of the unit of FIG. 10 shown together with means for filling and emptying a coolant, such as an oil, through a container for the unit. FIG. 16 is a vertical sectional view taken along section line 16-16 in FIG. 12. FIG. 17 is a schematic diagram illustrating how particulate material is fed into the plenum from each resilient wall tube as the helical member rotates and engages the tubes in successive sequences. 17... Resilient wall tube, 28... Tube roller, 39... Wheel, valve means, 42... Arc-shaped surface portion, 22... Chain, belt, 47... Plenum,
54... Vacuum source, 58... Container.

Claims (1)

Claims: 1. (a) feeding material along the length of a resilient walled tube having an open end into a feed end of said tube that is partially crushed against itself; (b) holding the tube in the tube above the tube's crushing point; (b) the tube's crushing point downwardly toward the discharge end so that the material in the tube can flow under its own weight down the length of the tube; (c) to prevent material from flowing into the tube;
closing the feed end of the tube; (d) crushing the tube against itself above the material already in the tube and near the feed end of the tube; (e) crushing the tube over and above the tube; re-expanding the collapsed portion of the tube near the discharge end of the tube to allow material in the tube held between the lower portion to be ejected; (f) additional material is added to the tube; A method for dispensing a fluid material, comprising the steps of: opening the dispensing end of the tube to allow flow into the dispensing end; and (g) repeating steps (a) to (f). 2. A unit for metering and supplying fluid material, said unit comprising: a fluid material receiving tube having an open end with an open supply end and an open discharge end and having an elastic wall; a power source positioned adjacent to the tube including tube rollers spaced apart to engage the tube in repeated cycles to crush a portion of the tube while acting progressively toward the beginning and discharge end; a drive assembly, the tube rollers disengaging from the tube at the discharge end to enable re-expansion of the tube and evacuation of material from the tube; synchronously with the power drive assembly so that when one of the tubes first engages the tube at the feed end, that portion of the tube is substantially free of material. A unit for metering and dispensing fluid material, characterized in that valve means are provided at the dispensing end next to the tube for preventing the dispensing of fluid material at intervals of time. 3. A unit according to claim 2, characterized in that the spaced tube rollers are mounted on an endless flexible driven belt. 4. Claim 2, characterized in that the valve means includes an arc-shaped rotatable member, said rotatable member having a surface that periodically covers and exposes the feed end of the tube upon rotation. Units listed in section. 5. The valve means are synchronously actuated to open the feed end of the tube after one of the spaced tube rollers collapses the tube near the feed end of the tube. 2
Units listed in section. 6 mounted between spaced apart tube rollers and substantially perpendicular to said tube rollers;
at least one pair of side rollers for engaging side walls of the tube, the side rollers engaging the side walls of the tube both before and after the tube is crushed by the tube rollers to assist in re-inflating the tube; A unit according to claim 2, characterized in that: 7. A plenum in communication with the discharge end of the tube and a source of pressurized gas flowing through the plenum to convey the discharged material into the plenum. unit. 8. A unit for metering and dispensing fluid material, said unit comprising at least one tube for receiving fluid material having an open end with an open supply end and an open discharge end and having an elastic wall;
a rotatable helical member disposed adjacent the tube and engaging the tube along the length of the tube so as to compress the tube against itself as the helical member rotates about its axis; a drive assembly, the helical member compressing a portion of the tube starting at the supply end of the tube and working progressively toward the discharge end so that the discharge end disengages from the tube and rejoins the tube. In said unit for permitting expansion and evacuation of material from the tube, valve means is provided at the feed end of the tube to prevent material from entering the feed end at predetermined intervals in synchronization with the power drive assembly, When the helical member of the drive assembly first engages and compresses the upper portion of the tube at the feed end, there is no material in that portion of the tube and the helical member engages the upper portion of the tube. after which valve means open the feed end to allow material to enter the feed end. 9. A unit according to claim 8, characterized in that it includes a plurality of vertically oriented resilient wall tubes arranged equidistantly around the axis of the helical member. 10. In order to ensure re-inflation of the tube after compression by the helical member, it includes means for making it possible to periodically vent the interior of the tube to the atmosphere. 9
Units listed in section. 11. A unit according to claim 9, characterized in that the tube is housed in a container, the container being filled with coolant. 12. Claim 8 including means for engaging and supporting the tube as the helical member progressively compresses the tube along its length. unit. 13 including means for preventing lateral movement of the tube when the helical member first engages the tube;
9. A unit according to claim 8, characterized in that: